La Nina Could Bring Mild, Dry Winter to Oklahoma

October has gotten off to a cool start in Oklahoma, including a few low temperatures that fell below freezing the last several days. Despite the cool beginning, however, the National Weather Service’s Climate Prediction Center (CPC) sees an increased chance for warmer- and drier-than-normal weather in Oklahoma during October. Looking farther out, the CPC indicates similar conditions could persist through the winter months, meaning a milder but possibly drier winter for Oklahoma. The culprit behind this possible disruption of Oklahoma’s weather is none other than El Niño’s counterpart, La Niña.

La Niña occurs when sea surface temperatures in the equatorial Pacific become cooler than normal. Much like El Niño, this cooling of sea surface temperatures can influence weather around the globe, including that of the United States. Impacts from La Niña include the tendency for a warmer and drier cool season in the southern United States, along with cooler and wetter conditions in the Midwest and Pacific Northwest. The current La Niña is expected to continue strengthening and remain in place throughout the 2010-11 winter season.

La Niña’s impacts on Oklahoma’s economy can be significant. A warmer and drier cool season can have adverse effects on Oklahoma’s agricultural industry. With the planting of next year’s wheat crop underway, moisture becomes a key ingredient for establishing that crop and developing it through to maturity. That wheat can also be used to provide forage during the winter months for cattle producers. Unfortunately, Oklahoma’s key wheat-producing areas are beginning to see dry conditions spread due to below normal rainfall over the last couple of months. Rainfall deficits due to La Niña’s influence would come at an inopportune time. Another negative impact of warmer and drier conditions is a possible increase in wildfires, which the state saw during the dry winter of 2005-06.

Not all La Niña impacts are necessarily negative. Cooler weather in the northern parts of the country can boost Oklahoma’s natural gas industry, and therefore its economy, by increasing demand and keeping prices higher. The state reaped that benefit last winter during a particularly cold and stormy winter in the eastern half of the country. Oklahoma residents, on the other hand, could see cheaper heating bills.

A warmer and drier winter does not necessarily translate into a season free of ice and snow. Significant individual ice and snow events can still occur within longer dry periods. For example, severe ice storms struck Oklahoma during the La Niña winters of December 2000 and 2007.

It is important to remember that each La Niña episode can develop differently and be influenced by other climate factors. However, increased confidence is present in long-range outlooks when La Niña or El Niño conditions are present, especially during the winter months.